1. Field of the Invention
This invention relates to a locking mechanism for electrical connector applied to connection of a wire harness for vehicles etc., provided with an engaging part being engaged with a locking part of a mating connector.
2. Description of the Related Art
FIG. 5 and FIG. 6 show an example (Japanese Non-examined Utility Model Application Publication No. Sho 64-49906) of prior art relevant to this kind of locking mechanism for connector.
As shown in FIG. 5, a pair of a male type connector 50 and a female type connector 60 are applied to various cables, such as a core wire of optical fiber. The male type connector 50 is provided with a male type connector housing 51 including an electric wire insertion hole (not shown) thereinto, an electric wire 70 of which an edge is inserted through the electric wire insertion hole, and a locking arm 53 is formed as protruding from an outer wall 51a of the male type connector housing 51 in a cantilever shape. The locking arm 53 comprises an operating part 54 for pressing, and a locking projection 55 located at a free end side succeeding to the operating part 54. An inclined surface 55a, which abuts against a fitting part 66 of the female type connector 60, is formed on the locking projection 55.
The female-type connector 60 is provided with a female type connector housing 61 including an engaging hood 64, a metal fitting 67 extended outside from an outer wall 61a of the female type connector housing 61, and the fitting part 66 formed on the engaging food 64.
In order that the male type connector 50 engages with the female type connector 60, the male type connector 50 is inserted into a engaging space 65 of the female type connector 60 while keeping the operating part 54 of the locking arm 53 pressed downward. Namely, pressing the operating part 54 downward allows the locking projection 55 to pass through the engaging space 65 with neither interference nor slidable contact with the engaging hood 64, thus a pair of connectors 50 and 60 can be engaged together with low insertion power.
In such an engaging state, when a pulling force acts on the connectors 50 and 60, the inclined surface 55a of the locking projection 55 abuts against the fitting part 66 of the engaging hood 64. Then, the locking projection 55 bends downward along the inclined surface 55a thereof. Then, the locking projection 55 comes out of the fitting part 66 and the engagement is released. Namely, the pair of connectors 50 and 60 can be unlocked easily by the pulling force. Therefore, such a locking mechanism prevents both the electric wire 70 from rupturing in the middle thereof and an electric wire connection part 56 fitting over an end of the electric wire 70 from being damaged.
However, in a conventional locking mechanism, such as above described, there is a problem to solve, as follows.
First, in engaging the connectors 50 and 60, when pressing down the locking arm 53 by depressing the operating part 54, the locking projection 55 is not moved perpendicularly with respect to a direction of connector engagement, but is moved inclinedly or in a circular orbit. Therefore, an engagement position between the locking projection 55 and the fitting part 66 may not be fixed. Thus, there is an anxiety that said engagement may be carried out with some play.
If such play exists, the pair of connectors 50 and 60 cannot retain tightness thereof. Especially in a waterproof connector, water droplets or dust may penetrate from a crevice therein to produce a poor connection so that the reliability of the electrical connection may be lost.
Additionally, there is another problem that engagement force of the pair of connectors 50 and 60 is weak. Namely, the inclined surface 55a is formed on the locking projection 55 of the locking arm 53. Thus, by pulling the electric wire 70 or connectors 50 and 60, the locking arm 53 bends downward, then the locking projection 55 comes out of the fitting part 66 and the engagement is released.
Therefore, in order to increase the engagement force of the pair of connectors 50 and 60, it is necessary to reduce resiliency of the locking arm 53 by increasing rigidity thereof, without modifying components-thereof. For attaining this, it is necessary that the locking arm 53 should have a thick body to improve section performance thereof. However, this structure makes a new problem that the locking arm 53 becomes larger and the male type connector 50 also becomes larger. Moreover, in engaging the pair of connectors 50 and 60 together, the locking projection 55 of the locking arm 53 rubs against an inner wall of the mating female type connector 60 and the insertion force required for joining the connectors 50 and 60 increases. Thus, the pair of connectors 50 and 60 cannot be engaged with each other smoothly.
Moreover, for releasing the engagement of the pair of connectors 50 and 60, it is necessary to extract the locking projection 55 from the fitting part 66 while bending the locking projection 55 of the locking arm 53 downward. However, if the locking arm 53 is hard to bend, the operating part 54 must be depressed with a strong power. Thus, operability of the locking arm 53 turns bad.
The present invention has been accomplished to solve the above-described problems and an object of the present invention is to provide a locking mechanism for an electrical connector that allows an engagement of connectors without any play, the engagement of connectors to prevent a reduction in engagement retaining power, and electrical terminals of the connectors to prevent a reduction in electrical contact quality.
In order to attain the above-described object, there is provided, according to a first aspect of the present invention, a locking mechanism of electrical connector that comprises one connector housing having a pair of projections facing with each other, one of the projections having a taper end, and the other connector housing having a locking part at a locking arm thereof, the locking part having an inverse taper rear end. In this locking mechanism, the locking part of the other connector housing is disposed in a space between the projections of the connector housing. Hereat, a front end of the locking part abuts against the taper end of the projection and the inverse taper rear end of the locking part abuts against an end of the other projection.
In this configuration, by inserting the locking part into the space between the pair of projections, clearance between the pair of projections and the locking part becomes zero. Thus, the play in the direction of the engagement of the connectors is canceled. Additionally, when the pulling force acts on the connector in the direction of the release of the connectors, the inverse taper rear end of the locking part thereof digs into the rear end of the projection of the other connector to improve a catch. Thus, this mechanism of the present invention prevents the connectors from being unlocked. Therefore, this mechanism prevents the reduction in the engagement retaining power and the reduction in the electrical contact quality. Additionally, this mechanism can prevent the connector from dropping out of the engagement. Thus, reliability of the lock of the connectors is improved.
Preferably, in the above described locking mechanism, the locking arm is supported by a middle fulcrum part and connecting parts. The middle fulcrum part is raised from the connector housing. The connecting parts connect to the connector housing. The locking part is positioned in between the middle fulcrum part and the connecting parts.
In this configuration, by supporting the locking arm by the middle fulcrum and the connecting parts, and by positioning the locking arm in between the middle fulcrum and the connecting parts, when the locking arm bends in an arch-shape, the locking part is not disposed in the direction of the engagement, but is disposed substantially perpendicularly. Thus, alignment of the locking part being engaged with the pair of projections can be done correctly. Therefore, by restricting the engagement position of the locking part, a locking mechanism of electric connector can be provided with high engagement reliability.
Preferably, in above-described locking mechanism, a gap is generated between a bottom of the space of the pair between projections, and the locking part, under the condition that the locking part is engaged with the pair of projections.
In this configuration, the gap is generated between the bottom of the space of the pair of projections and the locking part. Thus, the locking part is restrained by projections facing back and forth so as to stick thereto. Thus, the engagement of the connectors-has no-play. Therefore, problems, such as abrasion of the electric terminals or abnormal noise, are also dissolved.